I use the star ratings in Adobe to help me figure out my keepers. As such, it depends on the shoot and the purpose.
What I do is go through quickly and give a star to technically correct and aesthetically pleasing photos. If I have botched a camera setting, I really don't care about much else. The photo doesn't make it to the next round. Recycle those electrons before they become stale and crusty. :)
Next, I select all my one stars, and make them all two stars. Then, I go through again. This time, I'm looking for reasons to demote a photo. I have another photo that's close to being like the soon-to-be-rejected one, but the second one is better. I go through and ruthlessly remove stars. I filter on those that remain at two stars. If I still have too many, I'll promote to 3 stars and do the same approach as before. I rarely do this. 99% of the time, my keepers are at 2 stars. I don't need another round. I'll then rename all my keepers with my standard naming formula, and I'm ready to go the next step.
My objective isn't to make sure that X number of stars has the same meaning between shoots. I have no reason I'd want to find Y number of stars across shoots. I'm going through and looking for shots to delete. Yes, delete. If a photo doesn't get two stars using the above system, chances are very good that it won't be backed up, and it will be headed toward the trash. The only exception is if I'm someplace where I have lots of keepers of slightly different subjects, and I might want to go back at some time to re-edit. This happens when I'm spending a lot of time on location at a shoot. Other than that, once I make my edits above, the ones that didn't make the grade are deleted. So for the vast majority of my shoots, I'm left with 2 star images. :)
Hope this helps explain one approach.